Laxmi Kant Tiwari / mbed-dsp

Important changes to repositories hosted on mbed.com

Mbed hosted mercurial repositories are deprecated and are due to be permanently deleted in July 2026.

To keep a copy of this software download the repository Zip archive or clone locally using Mercurial.

It is also possible to export all your personal repositories from the account settings page.

Fork of mbed-dsp by mbed official

cmsis_dsp/TransformFunctions/arm_bitreversal.c@2:da51fb522205, 2013-05-30 (annotated)

Committer:
emilmont
Date:
Thu May 30 17:10:11 2013 +0100
Revision:
2:da51fb522205
Parent:
1:fdd22bb7aa52
Child:
3:7a284390b0ce
Keep "cmsis-dsp" module in synch with its source

Who changed what in which revision?

UserRevisionLine numberNew contents of line
emilmont 1:fdd22bb7aa52 1 /* ----------------------------------------------------------------------
emilmont 1:fdd22bb7aa52 2 * Copyright (C) 2010 ARM Limited. All rights reserved.
emilmont 1:fdd22bb7aa52 3 *
emilmont 1:fdd22bb7aa52 4 * $Date: 15. February 2012
emilmont 2:da51fb522205 5 * $Revision: V1.1.0
emilmont 1:fdd22bb7aa52 6 *
emilmont 2:da51fb522205 7 * Project: CMSIS DSP Library
emilmont 2:da51fb522205 8 * Title: arm_bitreversal.c
emilmont 1:fdd22bb7aa52 9 *
emilmont 2:da51fb522205 10 * Description: This file has common tables like Bitreverse, reciprocal etc which are used across different functions
emilmont 1:fdd22bb7aa52 11 *
emilmont 1:fdd22bb7aa52 12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
emilmont 1:fdd22bb7aa52 13 *
emilmont 1:fdd22bb7aa52 14 * Version 1.1.0 2012/02/15
emilmont 1:fdd22bb7aa52 15 * Updated with more optimizations, bug fixes and minor API changes.
emilmont 1:fdd22bb7aa52 16 *
emilmont 1:fdd22bb7aa52 17 * Version 1.0.10 2011/7/15
emilmont 1:fdd22bb7aa52 18 * Initial Version
emilmont 1:fdd22bb7aa52 19 * -------------------------------------------------------------------- */
emilmont 1:fdd22bb7aa52 20
emilmont 1:fdd22bb7aa52 21 #include "arm_math.h"
emilmont 1:fdd22bb7aa52 22 #include "arm_common_tables.h"
emilmont 1:fdd22bb7aa52 23
emilmont 1:fdd22bb7aa52 24 /*
emilmont 1:fdd22bb7aa52 25 * @brief In-place bit reversal function.
emilmont 1:fdd22bb7aa52 26 * @param[in, out] *pSrc points to the in-place buffer of floating-point data type.
emilmont 1:fdd22bb7aa52 27 * @param[in] fftSize length of the FFT.
emilmont 1:fdd22bb7aa52 28 * @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table.
emilmont 1:fdd22bb7aa52 29 * @param[in] *pBitRevTab points to the bit reversal table.
emilmont 1:fdd22bb7aa52 30 * @return none.
emilmont 1:fdd22bb7aa52 31 */
emilmont 1:fdd22bb7aa52 32
emilmont 1:fdd22bb7aa52 33 void arm_bitreversal_f32(
emilmont 1:fdd22bb7aa52 34 float32_t * pSrc,
emilmont 1:fdd22bb7aa52 35 uint16_t fftSize,
emilmont 1:fdd22bb7aa52 36 uint16_t bitRevFactor,
emilmont 1:fdd22bb7aa52 37 uint16_t * pBitRevTab)
emilmont 1:fdd22bb7aa52 38 {
emilmont 1:fdd22bb7aa52 39 uint16_t fftLenBy2, fftLenBy2p1;
emilmont 1:fdd22bb7aa52 40 uint16_t i, j;
emilmont 1:fdd22bb7aa52 41 float32_t in;
emilmont 1:fdd22bb7aa52 42
emilmont 1:fdd22bb7aa52 43 /* Initializations */
emilmont 1:fdd22bb7aa52 44 j = 0u;
emilmont 1:fdd22bb7aa52 45 fftLenBy2 = fftSize >> 1u;
emilmont 1:fdd22bb7aa52 46 fftLenBy2p1 = (fftSize >> 1u) + 1u;
emilmont 1:fdd22bb7aa52 47
emilmont 1:fdd22bb7aa52 48 /* Bit Reversal Implementation */
emilmont 1:fdd22bb7aa52 49 for (i = 0u; i <= (fftLenBy2 - 2u); i += 2u)
emilmont 1:fdd22bb7aa52 50 {
emilmont 1:fdd22bb7aa52 51 if(i < j)
emilmont 1:fdd22bb7aa52 52 {
emilmont 1:fdd22bb7aa52 53 /* pSrc[i] <-> pSrc[j]; */
emilmont 1:fdd22bb7aa52 54 in = pSrc[2u * i];
emilmont 1:fdd22bb7aa52 55 pSrc[2u * i] = pSrc[2u * j];
emilmont 1:fdd22bb7aa52 56 pSrc[2u * j] = in;
emilmont 1:fdd22bb7aa52 57
emilmont 1:fdd22bb7aa52 58 /* pSrc[i+1u] <-> pSrc[j+1u] */
emilmont 1:fdd22bb7aa52 59 in = pSrc[(2u * i) + 1u];
emilmont 1:fdd22bb7aa52 60 pSrc[(2u * i) + 1u] = pSrc[(2u * j) + 1u];
emilmont 1:fdd22bb7aa52 61 pSrc[(2u * j) + 1u] = in;
emilmont 1:fdd22bb7aa52 62
emilmont 1:fdd22bb7aa52 63 /* pSrc[i+fftLenBy2p1] <-> pSrc[j+fftLenBy2p1] */
emilmont 1:fdd22bb7aa52 64 in = pSrc[2u * (i + fftLenBy2p1)];
emilmont 1:fdd22bb7aa52 65 pSrc[2u * (i + fftLenBy2p1)] = pSrc[2u * (j + fftLenBy2p1)];
emilmont 1:fdd22bb7aa52 66 pSrc[2u * (j + fftLenBy2p1)] = in;
emilmont 1:fdd22bb7aa52 67
emilmont 1:fdd22bb7aa52 68 /* pSrc[i+fftLenBy2p1+1u] <-> pSrc[j+fftLenBy2p1+1u] */
emilmont 1:fdd22bb7aa52 69 in = pSrc[(2u * (i + fftLenBy2p1)) + 1u];
emilmont 1:fdd22bb7aa52 70 pSrc[(2u * (i + fftLenBy2p1)) + 1u] =
emilmont 1:fdd22bb7aa52 71 pSrc[(2u * (j + fftLenBy2p1)) + 1u];
emilmont 1:fdd22bb7aa52 72 pSrc[(2u * (j + fftLenBy2p1)) + 1u] = in;
emilmont 1:fdd22bb7aa52 73
emilmont 1:fdd22bb7aa52 74 }
emilmont 1:fdd22bb7aa52 75
emilmont 1:fdd22bb7aa52 76 /* pSrc[i+1u] <-> pSrc[j+1u] */
emilmont 1:fdd22bb7aa52 77 in = pSrc[2u * (i + 1u)];
emilmont 1:fdd22bb7aa52 78 pSrc[2u * (i + 1u)] = pSrc[2u * (j + fftLenBy2)];
emilmont 1:fdd22bb7aa52 79 pSrc[2u * (j + fftLenBy2)] = in;
emilmont 1:fdd22bb7aa52 80
emilmont 1:fdd22bb7aa52 81 /* pSrc[i+2u] <-> pSrc[j+2u] */
emilmont 1:fdd22bb7aa52 82 in = pSrc[(2u * (i + 1u)) + 1u];
emilmont 1:fdd22bb7aa52 83 pSrc[(2u * (i + 1u)) + 1u] = pSrc[(2u * (j + fftLenBy2)) + 1u];
emilmont 1:fdd22bb7aa52 84 pSrc[(2u * (j + fftLenBy2)) + 1u] = in;
emilmont 1:fdd22bb7aa52 85
emilmont 1:fdd22bb7aa52 86 /* Reading the index for the bit reversal */
emilmont 1:fdd22bb7aa52 87 j = *pBitRevTab;
emilmont 1:fdd22bb7aa52 88
emilmont 1:fdd22bb7aa52 89 /* Updating the bit reversal index depending on the fft length */
emilmont 1:fdd22bb7aa52 90 pBitRevTab += bitRevFactor;
emilmont 1:fdd22bb7aa52 91 }
emilmont 1:fdd22bb7aa52 92 }
emilmont 1:fdd22bb7aa52 93
emilmont 1:fdd22bb7aa52 94
emilmont 1:fdd22bb7aa52 95
emilmont 1:fdd22bb7aa52 96 /*
emilmont 1:fdd22bb7aa52 97 * @brief In-place bit reversal function.
emilmont 1:fdd22bb7aa52 98 * @param[in, out] *pSrc points to the in-place buffer of Q31 data type.
emilmont 1:fdd22bb7aa52 99 * @param[in] fftLen length of the FFT.
emilmont 1:fdd22bb7aa52 100 * @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table
emilmont 1:fdd22bb7aa52 101 * @param[in] *pBitRevTab points to bit reversal table.
emilmont 1:fdd22bb7aa52 102 * @return none.
emilmont 1:fdd22bb7aa52 103 */
emilmont 1:fdd22bb7aa52 104
emilmont 1:fdd22bb7aa52 105 void arm_bitreversal_q31(
emilmont 1:fdd22bb7aa52 106 q31_t * pSrc,
emilmont 1:fdd22bb7aa52 107 uint32_t fftLen,
emilmont 1:fdd22bb7aa52 108 uint16_t bitRevFactor,
emilmont 1:fdd22bb7aa52 109 uint16_t * pBitRevTable)
emilmont 1:fdd22bb7aa52 110 {
emilmont 1:fdd22bb7aa52 111 uint32_t fftLenBy2, fftLenBy2p1, i, j;
emilmont 1:fdd22bb7aa52 112 q31_t in;
emilmont 1:fdd22bb7aa52 113
emilmont 1:fdd22bb7aa52 114 /* Initializations */
emilmont 1:fdd22bb7aa52 115 j = 0u;
emilmont 1:fdd22bb7aa52 116 fftLenBy2 = fftLen / 2u;
emilmont 1:fdd22bb7aa52 117 fftLenBy2p1 = (fftLen / 2u) + 1u;
emilmont 1:fdd22bb7aa52 118
emilmont 1:fdd22bb7aa52 119 /* Bit Reversal Implementation */
emilmont 1:fdd22bb7aa52 120 for (i = 0u; i <= (fftLenBy2 - 2u); i += 2u)
emilmont 1:fdd22bb7aa52 121 {
emilmont 1:fdd22bb7aa52 122 if(i < j)
emilmont 1:fdd22bb7aa52 123 {
emilmont 1:fdd22bb7aa52 124 /* pSrc[i] <-> pSrc[j]; */
emilmont 1:fdd22bb7aa52 125 in = pSrc[2u * i];
emilmont 1:fdd22bb7aa52 126 pSrc[2u * i] = pSrc[2u * j];
emilmont 1:fdd22bb7aa52 127 pSrc[2u * j] = in;
emilmont 1:fdd22bb7aa52 128
emilmont 1:fdd22bb7aa52 129 /* pSrc[i+1u] <-> pSrc[j+1u] */
emilmont 1:fdd22bb7aa52 130 in = pSrc[(2u * i) + 1u];
emilmont 1:fdd22bb7aa52 131 pSrc[(2u * i) + 1u] = pSrc[(2u * j) + 1u];
emilmont 1:fdd22bb7aa52 132 pSrc[(2u * j) + 1u] = in;
emilmont 1:fdd22bb7aa52 133
emilmont 1:fdd22bb7aa52 134 /* pSrc[i+fftLenBy2p1] <-> pSrc[j+fftLenBy2p1] */
emilmont 1:fdd22bb7aa52 135 in = pSrc[2u * (i + fftLenBy2p1)];
emilmont 1:fdd22bb7aa52 136 pSrc[2u * (i + fftLenBy2p1)] = pSrc[2u * (j + fftLenBy2p1)];
emilmont 1:fdd22bb7aa52 137 pSrc[2u * (j + fftLenBy2p1)] = in;
emilmont 1:fdd22bb7aa52 138
emilmont 1:fdd22bb7aa52 139 /* pSrc[i+fftLenBy2p1+1u] <-> pSrc[j+fftLenBy2p1+1u] */
emilmont 1:fdd22bb7aa52 140 in = pSrc[(2u * (i + fftLenBy2p1)) + 1u];
emilmont 1:fdd22bb7aa52 141 pSrc[(2u * (i + fftLenBy2p1)) + 1u] =
emilmont 1:fdd22bb7aa52 142 pSrc[(2u * (j + fftLenBy2p1)) + 1u];
emilmont 1:fdd22bb7aa52 143 pSrc[(2u * (j + fftLenBy2p1)) + 1u] = in;
emilmont 1:fdd22bb7aa52 144
emilmont 1:fdd22bb7aa52 145 }
emilmont 1:fdd22bb7aa52 146
emilmont 1:fdd22bb7aa52 147 /* pSrc[i+1u] <-> pSrc[j+1u] */
emilmont 1:fdd22bb7aa52 148 in = pSrc[2u * (i + 1u)];
emilmont 1:fdd22bb7aa52 149 pSrc[2u * (i + 1u)] = pSrc[2u * (j + fftLenBy2)];
emilmont 1:fdd22bb7aa52 150 pSrc[2u * (j + fftLenBy2)] = in;
emilmont 1:fdd22bb7aa52 151
emilmont 1:fdd22bb7aa52 152 /* pSrc[i+2u] <-> pSrc[j+2u] */
emilmont 1:fdd22bb7aa52 153 in = pSrc[(2u * (i + 1u)) + 1u];
emilmont 1:fdd22bb7aa52 154 pSrc[(2u * (i + 1u)) + 1u] = pSrc[(2u * (j + fftLenBy2)) + 1u];
emilmont 1:fdd22bb7aa52 155 pSrc[(2u * (j + fftLenBy2)) + 1u] = in;
emilmont 1:fdd22bb7aa52 156
emilmont 1:fdd22bb7aa52 157 /* Reading the index for the bit reversal */
emilmont 1:fdd22bb7aa52 158 j = *pBitRevTable;
emilmont 1:fdd22bb7aa52 159
emilmont 1:fdd22bb7aa52 160 /* Updating the bit reversal index depending on the fft length */
emilmont 1:fdd22bb7aa52 161 pBitRevTable += bitRevFactor;
emilmont 1:fdd22bb7aa52 162 }
emilmont 1:fdd22bb7aa52 163 }
emilmont 1:fdd22bb7aa52 164
emilmont 1:fdd22bb7aa52 165
emilmont 1:fdd22bb7aa52 166
emilmont 1:fdd22bb7aa52 167 /*
emilmont 1:fdd22bb7aa52 168 * @brief In-place bit reversal function.
emilmont 1:fdd22bb7aa52 169 * @param[in, out] *pSrc points to the in-place buffer of Q15 data type.
emilmont 1:fdd22bb7aa52 170 * @param[in] fftLen length of the FFT.
emilmont 1:fdd22bb7aa52 171 * @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table
emilmont 1:fdd22bb7aa52 172 * @param[in] *pBitRevTab points to bit reversal table.
emilmont 1:fdd22bb7aa52 173 * @return none.
emilmont 1:fdd22bb7aa52 174 */
emilmont 1:fdd22bb7aa52 175
emilmont 1:fdd22bb7aa52 176 void arm_bitreversal_q15(
emilmont 1:fdd22bb7aa52 177 q15_t * pSrc16,
emilmont 1:fdd22bb7aa52 178 uint32_t fftLen,
emilmont 1:fdd22bb7aa52 179 uint16_t bitRevFactor,
emilmont 1:fdd22bb7aa52 180 uint16_t * pBitRevTab)
emilmont 1:fdd22bb7aa52 181 {
emilmont 1:fdd22bb7aa52 182 q31_t *pSrc = (q31_t *) pSrc16;
emilmont 1:fdd22bb7aa52 183 q31_t in;
emilmont 1:fdd22bb7aa52 184 uint32_t fftLenBy2, fftLenBy2p1;
emilmont 1:fdd22bb7aa52 185 uint32_t i, j;
emilmont 1:fdd22bb7aa52 186
emilmont 1:fdd22bb7aa52 187 /* Initializations */
emilmont 1:fdd22bb7aa52 188 j = 0u;
emilmont 1:fdd22bb7aa52 189 fftLenBy2 = fftLen / 2u;
emilmont 1:fdd22bb7aa52 190 fftLenBy2p1 = (fftLen / 2u) + 1u;
emilmont 1:fdd22bb7aa52 191
emilmont 1:fdd22bb7aa52 192 /* Bit Reversal Implementation */
emilmont 1:fdd22bb7aa52 193 for (i = 0u; i <= (fftLenBy2 - 2u); i += 2u)
emilmont 1:fdd22bb7aa52 194 {
emilmont 1:fdd22bb7aa52 195 if(i < j)
emilmont 1:fdd22bb7aa52 196 {
emilmont 1:fdd22bb7aa52 197 /* pSrc[i] <-> pSrc[j]; */
emilmont 1:fdd22bb7aa52 198 /* pSrc[i+1u] <-> pSrc[j+1u] */
emilmont 1:fdd22bb7aa52 199 in = pSrc[i];
emilmont 1:fdd22bb7aa52 200 pSrc[i] = pSrc[j];
emilmont 1:fdd22bb7aa52 201 pSrc[j] = in;
emilmont 1:fdd22bb7aa52 202
emilmont 1:fdd22bb7aa52 203 /* pSrc[i + fftLenBy2p1] <-> pSrc[j + fftLenBy2p1]; */
emilmont 1:fdd22bb7aa52 204 /* pSrc[i + fftLenBy2p1+1u] <-> pSrc[j + fftLenBy2p1+1u] */
emilmont 1:fdd22bb7aa52 205 in = pSrc[i + fftLenBy2p1];
emilmont 1:fdd22bb7aa52 206 pSrc[i + fftLenBy2p1] = pSrc[j + fftLenBy2p1];
emilmont 1:fdd22bb7aa52 207 pSrc[j + fftLenBy2p1] = in;
emilmont 1:fdd22bb7aa52 208 }
emilmont 1:fdd22bb7aa52 209
emilmont 1:fdd22bb7aa52 210 /* pSrc[i+1u] <-> pSrc[j+fftLenBy2]; */
emilmont 1:fdd22bb7aa52 211 /* pSrc[i+2] <-> pSrc[j+fftLenBy2+1u] */
emilmont 1:fdd22bb7aa52 212 in = pSrc[i + 1u];
emilmont 1:fdd22bb7aa52 213 pSrc[i + 1u] = pSrc[j + fftLenBy2];
emilmont 1:fdd22bb7aa52 214 pSrc[j + fftLenBy2] = in;
emilmont 1:fdd22bb7aa52 215
emilmont 1:fdd22bb7aa52 216 /* Reading the index for the bit reversal */
emilmont 1:fdd22bb7aa52 217 j = *pBitRevTab;
emilmont 1:fdd22bb7aa52 218
emilmont 1:fdd22bb7aa52 219 /* Updating the bit reversal index depending on the fft length */
emilmont 1:fdd22bb7aa52 220 pBitRevTab += bitRevFactor;
emilmont 1:fdd22bb7aa52 221 }
emilmont 1:fdd22bb7aa52 222 }